Methods and components for wing-to-fuselage integration

ABSTRACT

A method for wing-to-fuselage integration is disclosed. The method includes attaching a fitting to a wing box assembly of an aircraft at an early stage of integration and then attaching the fitting to a stub beam attached to a fuselage panel of the aircraft at a later stage of integration. The fitting eliminates the need to attach the stub beam directly to the wing box assembly.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 14/541,379, filed on Nov. 14, 2014, and issued as U.S. Pat. No.9,828,083, the entire contents of which are herein incorporated byreference as if fully set forth in this description.

FIELD

The disclosure is related to aircraft manufacturing and, moreparticularly, a method and apparatus for wing-to-fuselage integration.

BACKGROUND

During manufacturing, large sections of an aircraft are pre-fabricatedand then integrated together to create a complete vehicle. For example,a fuselage panel is attached to a wing box assembly during aircraftmanufacturing. The fuselage panel is a section of the aircraft's mainbody. The wing box assembly is the main load carrying component of anaircraft wing.

Normal fuselage-to-wing box attachments fulfill several requirementsincluding providing a pressure boundary and ensuring compatibledeflections between the assemblies in all directions. To attach thefuselage panel to the wing box assembly, a series of stub beams areoften connected between these two aircraft sections. This operation istime consuming because the fasteners used to attach the stub beams tothe wing box assembly are numerous and difficult to drill.

Another problem arises when there are titanium or other hard metalelements in the attaching joint. A drill is used to create fastenerholes through the stub beams and the wing box assembly. These fastenerholes traditionally penetrate the wing box assembly. When there are hardmetal elements in the joint, a specialized drill is required to drillthe harder metal and possibly to mitigate burrs generated duringdrilling. Unfortunately, the large size of the specialized drill neededwith hard metals interferes with the stub beam and the surroundingstructures making it nearly impossible to attach the fuselage panel tothe wing box assembly. Traditionally, these complex operations areperformed in the later stages of the aircraft manufacturing.

It is common that a portion of the wing box assembly is also a fuelcontaining vessel. In the case that the fasteners penetrate this wingbox assembly fuel boundary, many additional steps are required to cleanthe drilling contaminants from the fuel cell, seal the fuel boundary,and test the sealing.

Thus, a need exists to attach the fuselage panel to the wing boxassembly in a manner that simplifies the manufacturing process.

SUMMARY

Methods for wing-to-fuselage integration are disclosed. In one example,the method includes attaching a fitting to a wing box assembly,attaching a stub beam to a fuselage panel, placing the stub beamadjacent to the fitting, and attaching the stub beam to the fitting. Inanother example, the method includes attaching the fitting to the wingbox assembly, placing the fuselage panel adjacent to the wing boxassembly, attaching the stub beam to the fuselage panel, and attachingthe stub beam to the fitting. In another example, the method includesattaching a first wall of the fitting to the wing box assembly in anearly stage of aircraft manufacturing, and attaching a second wall ofthe fitting to the stub beam attached to the fuselage panel during alater stage of aircraft manufacturing. Beneficially, the stub beams arenot directly attached to the wing box assembly in these methods.

The features, functions, and advantages that have been discussed can beachieved independently in various embodiments or may be combined in yetother embodiments further details of which can be seen with reference tothe following description and drawings.

BRIEF DESCRIPTION OF THE FIGURES

Presently preferred embodiments are described below in conjunction withthe appended drawing figures, wherein like reference numerals refer tolike elements in the various figures, and wherein:

FIG. 1 is an illustration of a fuselage panel prior to integration witha wing box assembly, according to an example;

FIG. 2 is an illustration of the fuselage panel positioned forattachment to the wing box assembly, according to an example;

FIG. 3 is an illustration of a stub beam and fitting for attaching thefuselage panel to the wing box assembly, according to an example;

FIG. 4 is an illustration of a drill creating fastener holes forfitting-to-stub beam fasteners, according to an example;

FIG. 5 is an illustration of multiple fittings attached to the wing boxassembly, according to an example;

FIG. 6 is an illustration of a flow chart for a method ofwing-to-fuselage integration, according to an example; and

FIG. 7 is an illustration of a flow chart for a method ofwing-to-fuselage integration, according to another example.

The drawings are for the purpose of illustrating example embodiments,but it is understood that the inventions are not limited to thearrangements and instrumentality shown in the drawings.

DETAILED DESCRIPTION

The following description describes an aircraft manufacturing process.In particular, the description describes the wing-to-fuselageintegration process. The wing-to-fuselage integration process joins twolarge prefabricated pieces of an aircraft, specifically, a fuselagepanel to a wing box assembly. The wing-to-fuselage integration processoccurs twice, once for the left-hand side and once for the right-handside of the aircraft.

The wing box assembly is the main load carrying component of an aircraftwing. The wing box assembly typically extends through the fuselagesection of the aircraft. A portion of the wing box assembly may also bea fuel containing vessel. The fuselage panel involved in thewing-to-fuselage integration process is the body panel that is attachedto the wing box assembly.

It is understood that the benefits described herein apply to anyaircraft that requires wing-to-fuselage integration. As such, the terms“fuselage panel,” “wing box assembly,” and “stub beam” are generic termsthat are not limited to any particular aircraft type.

FIG. 1 is an illustration of a fuselage panel 100 prior to integrationwith a wing box assembly 200. The left-hand side fuselage panel 100 isshown in FIG. 1. A similar right-hand side fuselage panel is not shownin FIG. 1. While the wing-to-fuselage integration is shown in FIGS. 1-4with respect to the left-hand side of the aircraft, it is understoodthat a similar integration process on the right-hand side of theaircraft occurs during aircraft manufacturing.

FIG. 2 is an illustration of the fuselage panel 100 positioned forattachment to the wing box assembly 200. Typically, a jack holds thewing box assembly 200 in place. Then, a crane picks up and lowers thefuselage panel 100 into place. The crane has the ability to preciselyposition the fuselage panel 100 with respect to the wing box assembly200.

FIG. 3 is an illustration of a stub beam 300 and a fitting 400 forconnecting the fuselage panel 100 to the wing box assembly 200. Asdescribed further, the stub beam 300 is attached to the fuselage panel100, and the fitting 400 is attached to the wing box assembly 200 andthen later to the stub beam 300. While only one stub beam 300 and onefitting 400 are shown in FIG. 3, there are more than one stub beam 300and fitting 400 connections that occur during wing-to-fuselageintegration. The number of connections depends on the position andnumber of stub beams over the wing.

The stub beam 300 is sometimes referred to as a side frame as itprovides structural support for the fuselage panel 100. Specifically,the stub beam 300 is designed to withstand the forced deflection andflight loads from the aircraft's wings and pressure load from thefuselage.

The fitting 400 is an angle corner fitting. The fitting 400 includes twosurfaces that form a primary angle and two surfaces that formreinforcing walls or gussets. Stated another way, the fitting 400 isshaped as a three-dimensional triangle with a missing bottom. One planarside is attached to the wing box assembly 200 and the other planar sideis attached to the stub beam 300.

The fitting 400 is designed to maximize the amount of the fitting 400that is visible after installation so that the fitting 400 can bevisually inspected for fractures or other failures. Other fittingdesigns with at least two planar sides are possible, such as T-shaped orL-shaped fittings. The fitting 400 may be integral to another wingcomponent and there may be multiple fitting features integral to anotherwing component.

The fitting 400 is preferably formed using aluminum when the stub beam300 is formed using aluminum because aluminum is easy to drill and thelike materials are not prone to galvanic corrosion interactions. Thefitting 400 may be formed using other materials. For example, thefitting 400 may be formed using titanium, which may be preferable if theairframe is manufactured using titanium or carbon fiber reinforcedpolymer (CFRP). In the case that the wing box assembly interface withthe fitting 400 is not aluminum, the fitting material is best chosen tobe the anodic element in any galvanic interaction as the fitting 400 ismore easily repaired than the wing box assembly 200 or the stub beam300.

The fitting 400 may include four holes, two holes on each of the twosurfaces that form the primary angle. The first two holes are pilotholes for drilling fastener holes through the planar surface of thefitting 400 and into the wing box assembly 200. The other two holes arepilot holes for drilling fastener holes through the upright surface ofthe fitting 400 and into the stub beam 300. The fitting 400 may havemore or less than four pilot holes, including no holes at all. The holesmerely facilitate drilling.

FIG. 4 is an illustration of a drill 500 creating holes for fastenersconnecting the fitting 400 to the stub beam 300. Because the stub beam300 is attached to the fitting 400 and not to the wing box assembly 200,drilling access is easier and the wing box assembly 200 is notpenetrated. This allows the wing box assembly 200 to be sealed and leaktested prior to integration with the fuselage and, as a result, themanufacturing process is simplified. As depicted in FIG. 4, the drillhas clear access to the attachment location. Additionally, becausealuminum-to-aluminum drilling is easier than drilling into titanium, aspecialized titanium drilling apparatus is unnecessary.

FIG. 5 is an illustration of multiple fittings 400 connected to the wingbox assembly 200. The number of fittings 400 attached to the wing boxassembly 200 is based on the number of stub beams 300 connecting to thewing box assembly 200. In this example, the size of the fittings 400 canbe optimized for varying loads occurring from a leading edge end of thewing box assembly 200 to a trailing edge end of the wing box assembly200. The size of the fittings 400 depends on load transfer and forceddeflections between wing and fuselage. Multiple fittings could beintegral to a single wing component in lieu of individual fittings. Eachaircraft design has different wing/fuselage loads, which are used todesign the fittings 400.

FIG. 6 is a flow chart of a method 600 for wing-to-fuselage integration.At block 602, the fittings 400 are attached to the wing box assembly200. The fittings 400 may be attached by drilling holes and installingone or more fasteners through the planar surface of the fitting 400 andinto the wing box assembly 200. While two threaded nut bolts arepreferable for attaching the fittings 400 to the wing box assembly 200,other fastening mechanisms may be used.

At block 606, the wing box assembly 200 is deburred, sealed, and theseals are tested. By drilling into the wing box assembly 200 at thisearly stage in the manufacturing, burrs may be eliminated by takingapart the structure and performing conventional deburring. Burrs mayalso be mitigated by using a larger, specialized drill to drill throughan aluminum-titanium/CFRP stack. Also at block 606, sealing and testingof the wing box assembly 200 may be performed at an early stage in themanufacturing prior to integration with the fuselage.

At block 604, the stub beams 300 are attached to the fuselage panel 100.The stub beams 300 may be attached by drilling and installing multiplefasteners through fuselage panel 100 and into the stub beams 300. Otherfastening mechanisms may be used as appropriate for airframemanufacturing.

Block 602 and block 604 are shown next to each other to indicate thatthese two manufacturing steps could take place at two differentlocations. For example, a first vendor may supply the wing box assembly200 with the fittings 400 attached and a second vendor may supply thefuselage panel 100 with the stub beams 300 attached. As another example,only one of these airframe sections is outsourced and the other airframesection is manufactured in-house. While these two manufacturing steps602 and 604 can take place at substantially the same time, it is alsopossible for one airframe section to be manufactured before the other.

At block 608, the stub beams 300 are placed adjacent to the fittings400. In a typical airframe manufacturing process, a jack holds the wingbox assembly 200 in place, while a crane picks up and lowers thefuselage panel 100 in a precise manner as to place the stub beams 300adjacent to the fittings 400. The fittings 400 may be used as a guide inpositioning the fuselage panel 100 in relation to the wing box assembly200. Shims may be placed between the stub beams 300 and the fittings 400as necessary to allow for manufacturing differences.

At block 610, the stub beams 300 are attached to the fittings 400. Thefittings 400 may be attached by drilling holes and installing one ormore fasteners in the upright surface of the fitting 400 and into thestub beam 300. While two threaded nut bolts are preferable for attachingthe fitting 400 to the stub beam 300, other fastening mechanisms may beused.

In the method 600, the stub beams 300 are attached to the fuselage panel100 prior to placing the stub beams 300 adjacent to the fittings 400.Alternatively, the fuselage panel 100 may be placed in position withrespect to the wing box assembly 200 prior to attaching the stub beams300 to the fuselage panel 100. In this scenario, the shims placedbetween the stub beams 300 and fittings 400 may be reduced in thicknessor eliminated. This example is shown in FIG. 7.

FIG. 7 is a flow chart of a method 700 for wing-to-fuselage integration.At block 702, the fittings 400 are attached to the wing box assembly 200in a similar manner as described with respect to block 602. At block704, cleaning drilling contaminants from the fuel cell, sealing the fuelboundary of the wing box assembly 200, and testing the seal occur in asimilar manner as described with respect to block 606. As a result, themethod 700 provides the same advantages as the method 600 of moving thedrilling, sealing, and leak testing of the wing box assembly 200 toearlier in the manufacturing process.

At block 706, the fuselage panel 100 is placed adjacent to the wing boxassembly 200. A jack holds the wing box assembly 200 in place, while acrane picks up and lowers the fuselage panel 100 in a precise manner asto place the fuselage panel 100 adjacent to the wing box assembly 200.With the fittings 400 already attached to the wing box assembly 200, thefittings 400 may be used as a guide in positioning the fuselage panel100 in relation to the wing box assembly 200.

At block 708, the stub beams 300 are attached to the fuselage panel 100.The stub beams 300 are attached to the fuselage panel 100 is a similarmanner as described with respect to block 604. The difference here isthat the assembly tolerances between the fittings 400 and the stub beams300 may be managed differently, which in turn may reduce the thicknessof or eliminate the need for shims at block 710.

At block 710, the stub beams 300 are attached to the fittings 400 in asimilar manner as described with respect to block 610.

Using the fitting 400 in wing-to-fuselage integration changes the orderof the typical aircraft manufacturing process. In particular, drillinginto the wing box assembly 200 has been moved to earlier in the process,which has several benefits including performing sealing and leak testingearlier in the manufacturing process and allowing the wing boxattachment holes to be deburred, which improves fatigue life.Additionally, attaching the stub beams 300 to the fittings 400 is a muchsimpler process than attaching the stub beams 300 directly to the wingbox assembly 200. As a result, a smaller drill motor may be used and thetime required to perform this later step of manufacturing is reduced.Beneficially, the fitting 400 reduces the time and costs of aircraftmanufacturing.

It is intended that the foregoing detailed description be regarded asillustrative rather than limiting and that it is understood that thefollowing claims including all equivalents are intended to define thescope of the invention. The claims should not be read as limited to thedescribed order or elements unless stated to that effect. Therefore, allembodiments that come within the scope and spirit of the followingclaims and equivalents thereto are claimed as the invention.

What is claimed is:
 1. A method for wing-to-fuselage integration,comprising: attaching a fitting to a wing box assembly; attaching a stubbeam to a fuselage panel; placing the stub beam attached to the fuselagepanel adjacent to the fitting; and attaching the stub beam to thefitting, wherein the fitting is an angle comer fitting, and wherein thefitting is shaped as a three-dimensional triangle with a missing bottom,such that a first planar side of the fitting is directly attached to thewing box assembly and a second planar side of the fitting is directlyattached to the stub beam, wherein the fitting comprises two oppositetriangular-shaped side surfaces connecting the first planar side and thesecond planar side.
 2. The method of claim 1, wherein attaching thefitting to the wing box assembly includes drilling at least one fastenerhole in the fitting and the wing box assembly and fastening through thefitting and into the wing box assembly.
 3. The method of claim 2,further comprising: sealing the wing box assembly after attaching thefitting.
 4. The method of claim 3, further comprising: leak testing thewing box assembly after sealing.
 5. The method of claim 2, furthercomprising: deburring the wing box assembly and the fitting afterdrilling.
 6. The method of claim 1, wherein attaching the stub beam tothe fuselage panel includes drilling at least one fastener hole in thestub beam and the fuselage panel and fastening through the fuselagepanel and into the stub beam.
 7. The method of claim 1, whereinattaching the stub beam to the fitting includes drilling at least onefastener hole in the stub beam and the fitting and fastening through thefitting and into the stub beam.